I just received a Kiev 4M (Contax II or Contax III variant built in Ukraine with material repatriated from the Zeiss factory). This is the version with a selenium (or silicon?) Light meter On top of the camera, just under the accessory shoe. It is a "central needle" type, where the exposure is adjusted on a dial around the rewind button, with a film speed scale in the old Soviet Gost system (the value of Gost is 90% of ASA, so the film of Gost 100 would be ASA 90), and you measure by turning the exposure dial until the meter needle is on the diamond mark, then read the exposure (shutter and aperture values) of the scale and enter them on the lens and the speed dial 39; shutter.
It is a fairly simple meter to use and more practical than carrying a separate meter, although its limited sensitivity makes it less useful indoors (a very common problem with selenium meters).
What interests me is whether it is reasonably easy to adjust this counter to read 10% lower, so I can directly adjust the speed of the film to it ; ISO / ASA linear scale on the measurement scale.
There is a small screw inside a protective collar on the back of the top cover of the camera, under / behind the player. Is this screw to adjust the meter or the rangefinder? In the first case, is a 10% change in reading practical to apply with this screw?